Create calculated fields to serve as a "wrappers" for each of your measures that use an IF statement to decide which value to return based on the current parameter selection. For instance, the calculated field for the YTD 2014 field would look something like this...
IIF([ParameterName]='YTD', [YTD 2014], NULL)
Hope this helps!
I dont want a single time period. I need all YTD time periods.